This generally won’t affect users, but we wanted to be open about a change that will be deployed soon for our production servers. Essentially, we’re going to be defining a per-user disk quota for Firefox Sync, with the initial limit being 25 MB of data per user. For the vast majority of users, this will be completely invisible, since the typical user uses a lot less. (I’m a very heavy browser user, and I’m at around eight megabytes of usage.) We’ve attempted to answer some of the expected questions below, but anything else can go in the comments.
Why implement quotas?
We want to keep Firefox Sync as a free service for everyone. In order to make this viable, we have to take steps to control costs and prevent abuse. Implementing a reasonable default cap on disk usage is an obvious step in that direction. We believe the initial default will be sufficient for nearly all users.
How much of my data will I be able to sync?
In general, as much as you’re already syncing. Based on our current usage statistics, this quota will be enough for more than 99.9% of our users. The average user uses about 1 MB of data, with an average of 83 bookmarks, 11 passwords, and 1500 history items. Even around the 90th percentile of users, the disk usage is under 6 MB, with around 700 bookmarks, 12000 history items, and 100 passwords.
Can I get more space?
While the specifics have yet to be determined, one of the things we’re working on is a means to allow specific users to have a higher quota. In the meantime, it is already possible to request a quota increase via the Mozilla Services Account web page. We don’t yet have a timeline for if/when these requests will be fulfilled, but we’re using those inputs to help understand why users would need more quota to inform future designs.
Alternatively, for those more technically inclined, our server code is open source and can be installed on a server of your choice. For more information on this, please see the setup instructions.
What happens if I run out of space?
When a user passes the “warning” threshold (we expect to set this to 20 MB), the server will pass this information back to the client, so users get warned before they are unable to write to the server. If a user ignores these warnings and actually hits the cap, they will be unable to write any additional data to the server, and they will see Sync errors informing them of the problem. Firefox has UI that controls what type of data to sync, and how much each type of data is using. Users will be able to disable individual sync engines and free up space, if necessary.
— mconnor, on behalf of the Services team